Solid-state potentiometric thin film hydrogen gas sensors were successfully fabricated using a sol-gel-derived high proton-conducting P2O5-SiO2 glass films. Manganese oxide thin film coated on an indium tin oxide (ITO)-coated glass substrate was used for reference electrode. The sensor exhibited high speed responsibility within 10 s and 120 s at 30 oC and -30oC, respectively, for 1 vol.% hydrogen gas. A linear relationship between the electromotive force (EMF) and the logarithmic hydrogen concentration of 0.1~1 vol.% was obtained in the temperature ranging from -30 to 30 oC. The sensing mechanism was also discussed to improve the sensitivity and sensing speed against low H2 concentration at low temperatures.